No Winners In Battle Between Ad Blockers And Those Trying To Circumvent Them

8 August 2016 by Martin Delaney

stalemate4This article was originally published in AdExchanger on 1st August 2016.

Right now, there’s a war of code taking place between software engineers and hackers that will influence future industry decision-making.

On the one side, ad tech engineers battle to expose advertising to ad blocker users, and on the other side, ad blocker administrators fight to remove it.

This conflict is largely obscured from view, buried and masked in lines of code and forum discussions not typically accessed by consumers or ad executives.

Notably, the nature and intensity of this warfare has escalated in recent times – to a point where we are deep in uncharted territory.


Originally, domain switching was the favored technique by ad tech engineers to circumvent ad blockers.

Since ad blockers rely upon a blacklist of ad server filters to identify and prevent ad calls from being made, simply changing an ad server domain to one not on a filter list was a way to get around this problem.

However, it is pretty straightforward for ad block administrators to add the new ad server domain to their filter lists. When this happens, the ad server is blocked again, and so a new domain is needed.

This cycle of domain switching and counter-blocking continued for many months and eventually came to a halt when the ad block administrators decided to change their strategy. They’d had enough.

A Barrier Is Erected

Instead of blocking only the third-party ad server domains listed on the ad filter lists, publishers that participated in domain switching had full third-party script blocks placed against their websites. This means that, whatever third-party domain is used for an ad server, it would get blocked by default. The domain switching game was over.

For the ad block administrators, implementing a full third-party block is a heavily manual process. Since a lot of essential non-ad-related content is loaded from third-party domains, all of these services have to be whitelisted and maintained indefinitely for every affected website.

To further discourage publishers from circumvention activity, audience analytics software, such as Google Analytics, and market research beacons, such as ScorecardResearch, are deliberately not being whitelisted. As a result, ad-blocking visitors become invisible within these services for the afflicted websites. At their own discretion, ad blockers could feasibly expand upon this list of sacrifices.


In response, ad tech engineers developed methods to deliver ad payloads that do not rely upon third-party ad calls. Most are based around principles of stitching ad content into editorial content server-side or transmitting ad content via an unorthodox medium that limits the capacity of ad blockers to interfere with it.

For now, the default counterattack response to this activity by the ad blockers remains the same: Hit publishers with a full third-party script block. Site-specific blocks will also be administered, but the effectiveness is usually short-lived.

Although the ad payloads are not categorically blocked, these circumvention methods can be characterized as a “hostage-taking” approach. Ultimately, publisher content is leveraged as a bargaining chip against the ad blockers. To categorically block the ads, editorial content, or at least part of it, must also be taken out with it.

This could force ad blockers to evolve from arbiters of digital advertising to arbiters of digital content in general. Access to editorial content may be guarded or revoked, selectively, if it is intertwined with a circumvented ad experience that exposes users to undesirable levels of intrusiveness or perceived risks to their privacy and security. Web browsers, such as Google Chrome, already provide similar services to this with “This site may harm your computer”-style notifications.

Bad Experience

As both sides fight to assert their own agenda over the end consumer, user experience deteriorates in the process – making neither side a winner.

Legitimate site content often gets blocked temporarily due to false positives, the result of an aggressive and cavalier ad-blocking tactic that accidentally removes editorial content or site functionality in addition to the intended advertising. Ad units also frequently come laden with unwanted side effects, including slow load times, broken assets and mistargeting.

Added to the mix, brands are hesitant to force their ads upon unwilling recipients, especially if basic quality controls cannot be guaranteed or met. This could leave mostly unbranded, lower-quality, direct-response buyers bidding for the inventory.

Questionable Sustainability

Forcing an ad through is one thing; making it worthwhile is another. Crucially, there are a number of serious data, verification and ad delivery limitations in a circumvented environment. This removes a lot of value for advertisers and thus the amount they are willing to pay for the inventory.

Although these limitations can be worked on technologically and mitigated over time, so too will the counter-blocking efforts by the ad blockers. Inevitably, no one is invulnerable to the effects of the cat-and-mouse game.

This is, ultimately, the greatest weakness of ad circumvention: volatility.

Publishers and ad tech companies are not able to build a solid foundation of code and practices if the ad-blocking community is constantly evolving tactically and technologically to overcome them.

This results in a never-ending paradigm of constantly changing ad-serving infrastructure upon which a flourishing and sustainable ad ecosystem cannot fundamentally be built.